Field of the Invention
The present invention relates to a printing apparatus and a data transfer method, and particularly to, for example, a printing apparatus which prints on a print medium by using an inkjet printhead and a data transfer method between the printhead and the printing apparatus.
Description of the Related Art
A conventional inkjet printhead (to be referred to as a printhead hereinafter) includes a plurality of orifices which discharge ink, heaters corresponding to the orifices, a sub-heater which warms up the overall printhead, and a plurality of diode sensors which measure the temperature of the printhead.
The following data are required for printing control of a printing apparatus which performs printing by using a printhead mounted on a carriage which reciprocally moves. That is, the required data include print data for selecting orifices, of the plurality of orifices provided in the printhead, from which ink should be discharged, and heat pulse data for driving the heaters at the selected orifices. In addition, the required data include sub-heater control data for driving/controlling the sub-heater and diode sensor selection data for selecting a desired sensor from a plurality of diode sensors.
Of the above data, the print data and the heat pulse data are data which need to be transferred from the main body unit of the printing apparatus to the printhead for each discharging operation in accordance with the discharge timing of the printhead. In contrast to this, the sub-heater control data and the diode sensor selection data are data which need not be transferred for each discharge timing of the printhead and are allowed to be transferred at given predetermined intervals longer than the period of the discharge timing. For example, Japanese Patent Laid-Open No. 2010-131787 discloses an arrangement for performing sub-heater control independently of ink discharge control.
In order to control the printhead, a plurality of signal lines are provided between the printhead and the controller of the main body unit. Reducing the number of such signal lines will lead to the downsizing of an FFC (Flexible Flat Cable) which connects them, and hence is an effective means for achieving a reduction in the cost of the printing apparatus. As a means for reducing the number of signal lines, for example, data conventionally controlled by two signal lines may be integrated into data to be controlled by one signal line. In this case, however, the amount of data to be transferred through one signal line increases. Japanese Patent Laid-Open No. 2013-107341 has proposed a technique employing the LVDS scheme as a high-speed data transfer means for discharging ink at a timing similar to that in the related art without increasing the number of signal lines in a case where the amount of data transferred to the printhead has increased.
For example, it is possible to further reduce the number of signal lines by transferring sub-heater control data and print data through the same signal line.
According to the related art described above, however, an increase in the amount of data transferred through the same signal line makes it impossible to accommodate all transfer data within a time interval during which data should be transferred to the printhead. In a case where a carriage speed is increased to implement high-resolution, high-speed printing, in particular, a time interval assigned to data transfer to the printhead is shortened. In this case, obviously, the above problem occurs.